been operating at that level for much
longer, since about 2003, and has more
data, Green says. The LHC, which CERN
expects to roughly triple its beam intensity in 2011, will soon catch up, he adds.

To explore other new physics, such as
possible hidden dimensions or supersymmetry — the notion that every known
subatomic particle has a heavier, yet-to-be-discovered counterpart — the higher
energy of the Large Hadron Collider provides a huge advantage, Green says.

Because the two accelerators hunt
for the Higgs in different ways—the
Tevatron would detect the proposed
particle’s most common decay products,
a bottom quark and its antiparticle, while
the Large Hadron Collider would record
a rarer decay mode that produces two
photons—the searches are not only
competitive but complementary. “It
would have been very intriguing to see
the Higgs” at both atom smashers and
compare results, notes Söldner-Rembold.

Green adds that the lower energy of the
Tevatron produces a lower background
of extraneous particles, making its Higgs
search “a somewhat cleaner” process.

“If we get at the Higgs with the LHC
it will be with higher backgrounds,

The Higgs boson, if it exists, would
explain the origin of mass. Physicists
hope to see a signature of the particle
(simulation above) at the LHC when its
proton beams reach higher intensity.

meaning that it will take us longer to dig
it out,” Green says.

Because the Tevatron collides protons
with antiprotons, it’s also better suited
than the LHC to explore ideas about
why nature contains so much more matter than antimatter (SN: 6/19/10, p. 8).
The Tevatron has produced a number
of strange hints about nature’s asymme-tries that might have been confirmed by
an extended run.

Theorist Neal Weiner of New YorkUniversity agrees that “there are somethings that may be delayed, or be diffi-cult to study at the LHC.” But, he adds,“the field remains extremely exciting,both for the results still to come fromthe Tevatron and the exciting discover-ies that hopefully await us at the LHC.”Cosmologist Rocky Kolb of the Univer-sity of Chicago is philosophical about theTevatron’s demise. “All great acceleratorshave an end,” he says. “Any disappointmentat the closing of the Tevatron is temperedby my wonderful memories of my time atFermilab, when the Tevatron was crankingout discoveries and it was the center ofthe high-energy physics world.”Those highlights include the 1995discovery of the top quark, the sixth andlast discovered quark predicted to existaccording to current theory. Quarks area fundamental building block of matter.

Back Story
A TALE OF T WO COLLIDERS

A side-by-side comparisonof the soon-to-be-shutteredTevatron and the recentlycommissioned LHC.SOURCE: FERMILAB, CERN